Doctor Strange explains to us that the portal he opened in Las Vegas attracted not only Mephisto, but also Dormammu, Nightmare, and Shuma-Gorath. They warred over who would enter our dimension, and Mephisto won, which left the other three in some sort of Necro-Realm. Dormammu has a proposal for Doctor Strange and the Avengers. Stephen and Dormammu are each too weak to leave the Necro-Realm on their own, but, together, they may be able to share their power to leave. Strange realizes this may be his only way out, but he fears this may leave the door open for Dormammu to arrive on Earth.
Doctor Strange #389 provides a more backstory for Damnation, even if none of this is directly relevant to the events of Damnation. That said, it does give Strange something to do while Wong and Ghost Rider do all the plot relevant stuff in Damnation and Johnny Blaze: Ghost Rider.
I will almost never complain about an excuse to have Dormammu and Shuma-Gorath in a story. The stakes never feel too high, admittedly. Dormammu claims to be weak, and he's oddly casual and conversational with Stephen.
Strange's victory is distinctly Strange, so it works well for the story. It's a decently fun read.
Niko Henrichon continues to be an all-star in this book, as his artwork is one of the main things that makes this book a worthwhile read. The story is decently enjoyable, as I said. However, the art is where the book really shines. Henrichon's style is unique, ethereal, and textured in a way that is perfectly suited to Doctor Strange. The color work of he and Laurent Grossat adds to that ethereal and textured look with graded and eye-catching shades.
Doctor Strange #389 is a fun enough read. It has some laughs, the scenario is interesting, and the art is great. I can recommend this one easily enough. Feel free to check it out.